Thunderbolt to gigabit Ethernet adaptor connected but no Internet

Hello, I have a MacBook Air which is brand new and am currently in university accommodation which means I am using an Ethernet cable along with the thunderbolt adapter to connect to the internet (not wi-fi).

However I've connected the thunderbolt adapter and though in system preferences>network it said the thunderbolt Ethernet has a self-assigned IP address and will not be able to connect to the internet. I then tried - in advanced settings - setting the 'configure IPv6' to link-local only, and for a while the thunderbolt adapter was listed as 'connected' with a green light. I switched the wifi off also. However despite the connected thunderbolt there was still no internet - couldn't get onto any sites. I also tried renewing DHCP lease to no avail. Now I have just looked again and the status is connected but with a self assigned IP address again!! This is with the link-local only selected.

Please help!

Thanks x